FR2539740A1 - New carbonate polyethers carrying cyclic carbonate groups, extractant organic composition based on these compounds and process for extracting metal values from these compositions - Google Patents

Abstract

New carbonate polyethers carrying cyclic carbonate groups of general formula: in which: R1 is a hydrocarbon group containing 2 to 10 carbon atoms, substituted by at least one chain R2 or R3, which are identical or different, are linear or branched alkyl groups containing 2 to 20 carbon atoms or aromatic groups optionally substituted by one or a number of lower alkyl radicals, n and p are independently of each other between 0 and 40 but are not both zero simultaneously. These new carbonate polyethers, dissolved in an aromatic solvent, form organic solutions which extract many metal values.

Description

New carbonate polyethers carrying cyclic carbonate groups, extracting organic composition based on these compounds and method of extracting metal values from these compositions.

 The invention relates to new carbonate polyethers carrying cyclic carbonates, the organic compositions especially useful as extracting solutions of metal values. in particular, based on these compounds and a method of extracting metal values from these compositions.

The subject of the invention is also a process for producing these new carbonate-polyethers bearing cyclic carbonate groups.

French Patent No. 2,453,859 of the Applicant already describes carbonatepolyethers carrying cyclic carbonate groups that can be used as extractants, in particular gold.

These polyethers may correspond to a polyoxyethylene or a polyoxypropylene terminated by cyclic carbonate and carbonate functions.

These are soluble in chlorinated solvents such as chloroform, 1,2-dichloroethane and 1,2,2-trichloroethane, but, on the other hand, are insufficiently soluble in aromatic solvents which limits their use in certain applications. industrial.

Surprisingly, it has been found that a particular family of carbonate-polyethers carrying cyclic carbonate groups, has extractant properties of similar metal values and furthermore could be soluble in industrial solvents comprising aromatic products.

Thus an object of the invention is to provide new polyethers that can be used industrially to extract the metal values, especially gold.

Another object of the invention is to provide a method for separating metal values from an aqueous solution containing them by liquid-liquid extraction.

dans laquelle : R1 est un groupement hydrocarbyle comportant 2 à 10 atomes de carbone, substitué par au moins une chaîne

According to the invention, the new carbonate-polyethers bearing cyclic carbonate groups correspond to the general formula

wherein: R1 is a hydrocarbyl group having 2 to 10 carbon atoms, substituted by at least one chain

R 2 or R 3, which may be identical or different, are linear or branched alkylene groups containing 2 to 20 carbon atoms or aromatic groups optionally substituted by one or more lower alkyl radicals, n and p are independently between 0 and 40 but not zero simultaneously.

ou R1 et R2 ont les significations données à la revendication 1, des groupes OH remplaçant les groupes

éventuels, a' une température comprise entre 100 et + 200 C et en présence d'un accepteur diacide.The invention also relates to a method for synthesizing carbonatepolyethers according to the invention, characterized in that 2,3-carbonyl-2,3-dipropylcarbonyl chloroformate is reacted with an alcohol alone or in a mixture of general formula

or R1 and R2 have the meanings given in claim 1, OH groups replacing the groups

optionally, at a temperature between 100 and 200 C and in the presence of a diacid acceptor.

One of the advantages of these compounds is that they are soluble in aromatic solvents. Thus, the invention also relates to a composition, especially useful as extractant solution of metal values, characterized in that it comprises at least one aromatic solvent and at least one compound according to the invention.

The invention also relates to a method for separating metal values from an aqueous solution containing them by liquid-liquid extraction, characterized in that said aqueous solutions are brought into contact with an organic solution as described above so that at least a portion of the metal values are extracted by the organic solution and then the aqueous solution is separated from the organic solution and the metal values contained in the organic solution are recovered by bringing the latter into contact with the organic solution. an aqueous stripping medium.

Suitable compounds for the present invention are, for example, polyoxybutylene-1,2, polyoxypentyl-1-1,2, polyoxyhexylene-1,2,3,3, 3,4, terminated in groups. carbonates of radicals carrying cyclic carbonates or adducts of the aforementioned compounds on a diol such as ethylene glycol or a triol such as glycerol or trimethylolpropane or aromatic polyethers resulting from the presence of an aromatic group grafted on the chains alkyleneoxy compounds such as polyoxystyrene.

It is obvious that the invention also includes the mixture of these compounds because during the synthesis of the polymer, the polyether obtained has not a single structure but on the contrary several statistically distributed.

dans laquelle R2 et R3 ont la même signification et n et p sont indépendamment compris entre O et 40 mais non nuls simultanément.The carbonate-polyethers bearing cyclic carbonate groups having the general formula will be preferred.

wherein R2 and R3 have the same meaning and n and p are independently 0 to 40 but not zero simultaneously.

It has been found that it is particularly advantageous to use, among the compounds of the invention, those for which R 2 and R 3 are an alkyl group comprising two to four carbon atoms or a phenyl group optionally substituted by a lower alkyl radical and for which n and p are independently 0 to 20 but not zero simultaneously.

Indeed, the presence of these groups improves the hydrophobicity of the compounds of the invention and thus allows a good separation of organic and aqueous phases necessary for the main application described later for which these products are intended.

By lower alkyl radical is meant those which contain not more than four carbon atoms.

n et p étant indépendamment compris entre O et 20 mais non nuls simultanément.Of these, the following two families of compounds will advantageously be selected

n and p being independently between 0 and 20 but not zero simultaneously.

All the same, the compound containing the compounds will be preferred. ethyl groups
With respect to the synthetic process, the acid acceptor may be a mineral or organic base, however, it will be preferred to use an organic base such as aliphatic or aromatic tertiary amines such as triethylamine or pyridine.

A solvent is preferably but not necessarily used as the reaction medium. As a suitable solvent, mention may be made of the organic solvents of the alcohols and polyols concerned and 2,3-carbonyl-2,3-propyl chloroformate which are inert with respect to these reagents as well as to the acceptor of the 'acid. There may be mentioned, for example, aliphatic and aromatic hydrocarbons such as hexane, benzene, toluene, xylene, ethers such as tetrahydrofuran, or glymes, ketones such as acetone or cyclohexanone, or esters such as ethyl acetate. However, halogenated hydrocarbons such as carboxyl tetrachloride, chloroform, dichloromethane are preferred.

 The proportions of reagents to be used are those corresponding to the stoichiometry of the reaction, that is to say that at least one mole of chrifoformate is reacted per mole of hydroxyl carried by the alcohol, in the presence of an equimolar amount. acid acceptor. Preferably, a slight excess of chloroformate of preferably 5% to 15 molar% and a corresponding excess of acid exchanger will be used.

By at least partly aromatic solvent capable of solubilizing the compounds of the invention is meant either aromatic solvents such as benzene, toluene, xylene, pseudo cumene, tetralin (R) alone or in mixture or a mixture solvents of which at least a part consists of aromatic solvents.

A particularly interesting solvent because it is accessible in industrial quantities is the "Solvesso 200" (R) of the company ESSO.

Preferably, the compound will be present at a concentration of between 10 g and 180 g per liter of solvent. It is indeed in this interval that the composition proves to be the most useful for extracting the metallic values.

During extraction, as the gold concentration increases, there appears a third oily phase which it is advantageous to remove by adding to the solution, in a proportion equal to or less by weight than 10% relative to the solvent, a trialkylphosphate such as tributylphosphate (TBP). Surprisingly, it has indeed been found that only this family of products makes it possible to achieve the desired result while compounds such as nonylphenol or triarylphosphates do not produce the desired effect.

In order to preserve the extraction selectivity of the solution, it is however preferable not to exceed a concentration of TBP greater than 10%, preferably between 2 and 10 8.

The appearance of this third phase is also pushed back to a higher concentration of gold by increasing the extractant concentration.

With regard to the method for separating metal values, those which are most suitable are the following metal ions:
Zn (II), -Cd (II), Hg (II), Fe (III), Co (II), Cu (I), Rh (III),
Cu (II), Pd (II), Pt (II), Mo (V), V (IV), Pb (II), Ag (I), Au (III),
Ga (III) as well as Na (I), Cl (I), Hq (I), U (IV), U (VI) and lanthanides at the oxidation (II), (III) or (IV) levels,
It should be noted that the organic solutions according to the invention have a particularly high selectivity vis-à-vis lgor in the presence of platinum.

The stripping or separation of the metallic value of the organic phase may be carried out by washing with an optionally acidified aqueous phase, and preferably with an aqueous solution of an organic acid such as oxalic acid, at a concentration preferably between 1 and 10% by weight relative to the aqueous solution.

It has been found in this connection that the organic layers thus re-extracted have the advantage in a subsequent extraction operation of pushing back the limit from which a third phase appears.

A preferred variant consists in bringing the organic phase into contact with an acidic aqueous phase, preferably charged with sodium chloride.

Given the very good behavior of the compositions of the invention during their reuse the invention also has the advantage of allowing the use of the continuous extraction process.

The examples below illustrate the invention.

The synthesis of 2,3-carbonyldioxypropyl chloroformate is carried out according to French Patent No. 2,453,859.

Example 1 a) Preparation of polyhexaoxybutylene-1,2 glycol (n + p = 6)

2 g of ethylene glycol 3 and 600 cm 3 of CHCl 3, which are also used to rinse the ethylene glycol container, are introduced into a two-liter reactor with agitator, ascending refrigerant, thermometer and dropping funnel. Stir and heat to obtain 500C in the
3 reaction medium and then introduced 3 cm 3 of BF3 etherate. When the temperature of the reaction medium reaches 65 ° C., a solution of 432 g of butylene oxide in 600 cm 3 of CHCl 3 is poured.

The casting speed is controlled by the temperature of the reaction medium which must not exceed 700C. The reaction is exothermic and the temperature is maintained with an ice-water bath.

After the end of the casting, two hours are left at 70 ° C. and 75 ° C. The end of the reaction is controlled by the absence of epoxy potentiometric titration.

After cooling, the reaction medium is treated with an aqueous solution of NaOH at 5, in order to eliminate the etherate from
BF3. After decantation, washing with distilled H.sub.2 O to obtain PH.sub.7, the chloroform solution, decanted, is dried over magnesia sulfate, then filtered on a sintered G 3.

The filtrate is concentrated first under reduced vacuum - 0.019 bar (15 torr) then under a vacuum of 6.6 10-4 bar (0.5 torr). Bath-Marie temperature: 60 to 650C.

453 g of very clear product are obtained after filtration on paper filter, a slight precipitate being in suspension. The yield is 92%.

Analytical result: OH level: 4.12 eq / Kg
Mass: 485.

b) Synthesis of 1,2-hexaoxybutylene-1,2-di (2,3-carbonyldipropyl carbonate) glycol (n + p- = 6).

In a reactor, polyoxybutylene glycol (excess 10%) and then CH 2 Cl 2 (2.5 liters per 900 g of polyoxybutylene glycol) are introduced. Stir and cool. Excess pyridine is introduced. When the temperature of the reaction medium reaches -10.degree. C. to 15.degree. C., the starting point of the flow of 2,3-carbonyldioxypropyl chloroformate is 50-50 in solution in CH.sub.2 Cl.sub.2. The casting speed is a function of the temperature of the reaction medium which must not exceed -10 C. After the end of the casting, it is allowed to return to ambient temperature: the reaction medium is in milky form. The pyridine hydrochloride, formed very fine, remains in suspension. From this, we add distilled water to dissolve it and then decanted. Decantation proves difficult because a flocculated product remains in suspension (identified as a carbonate) but after a lapse of time, it precipitates. The settling waters are taken up with CH 2 Cl 2 and the combined organic phases are treated with a solution of 10% NaOH and then washed with distilled water until pH 7 is obtained. the organic phase thus treated is dried over magnesium sulphate, filtered on sintered glass G3, concentrated on a rotary evaporator and then vacuum-etched under a pallet pump
- Vacuum: 6.6 10-4 BARS (0.5 Torr)
- Temperature of the bath Marie o 800 C.

The yield is of the order of 85 to 90% O Formula

Example 2
Synthesis of 2,3-di (2,3-carbonyldipropylcarbonate) octahydbutylene-1,2-glycol.

The synthesis is the same as before except that octaoxybutylene-1,2-glycol (n + p = a) is used as glycol.

Yield: 90%
Example 3
Synthesis of hexaoxystyrenolglycol di (carbonyldioxy-2,3-propyl carbonate).

The synthesis is the same as above except that hexaoxystyrolene glycol (n + p = 6) is used as the glycol.

Yield: 90%
Formula

Examples 4 and 5
Extraction of gold for an extractant concentration of 50 g / l.

Two gold solutions were prepared reproducing industrial solutions usually encountered.

These solutions to extract have the following compositions
AB
Au: 5 g / l Au: 5 g / l
HCl. 3M HCL: 3M
CL: 3 M NaCl: 2.5M
Cl: 5.5M
One volume of these aqueous solutions was mixed with a volume of a 50 g / l solution of compounds according to the invention in various solvents.

After stirring the two phases, at room temperature, the percentage of gold extracted from the aqueous phase and present in the organic phase was measured. The results are collated in the following tables
Example 4: Solution A
% Excerpt

<tb><SEP> Thinners <SEP> Compound <SEP> Compound <SEP> Compound
<tb><SEP> of <SEP> the ex. <SEP> 1 <SEP> of <SEP> the ex. <SEP> 2 <SEP> of <SEP> the ex. <SEP> 3
<tb> Toluene <SEP> 60.4 <SEP> 76.6 <SEP> 15.4
<tb> Xylene <SEP> 73 <SEP> 77.9 <SEP> 32.6
<tb>"Solvesso<SEP>200"<SEP> 76.4 <SEP> 63.6 <SEP> 15.1
<tb><SEP> (R)
<Tb>
Example 5: Solution B
In extract

<tb><SEP> Thinners <SEP> Compound <SEP> Compound <SEP> Compound
<tb><SEP> of <SEP> the ex. <SEP> 1 <SEP> of <SEP> the ex. <SEP> 2 <SEP> of <SEP> the former <SEP> 3
<tb> Toluene <SEP> 90.3 <SEP> 62.3
<tb> Xylene <SEP> 92.4 <SEP> 64.9
<tb>"Solvesso<SEP>200"<SEP> 93.1 <SEP> 95.4 <SEP> 60.8
<tb><SEP> (R)
<Tb>
Example 6
Extraction of gold for an extractant concentration of 50, 100 and 150 g / l.

A volume of aqueous solution B was mixed with a volume of 50 100, 150 g / l of the compound of Example 1 in the "SOLVESSO 200" supplemented with an additive (5% TBP). After stirring the two phases at room temperature, the percentage of gold extracted from the aqueous phase and present in the organic phase was measured.

The results are summarized in the following table
Concentration of the compound of ex. 1 50 g / l 100 g / l 150 g / l% Au extract 97.9 # 99 # 99
Increasing the extractant concentration has little effect on the level of extracted mind but is of particular interest for the gold charge of the organic phase that can be achieved and moreover the appearance of a third phase is all the more delayed as the concentration of extractant is higher, which is reflected in the following table
Concentration of the gold charge corresponding to the compound of ex. 1 formation of a third phase
50 g / l to 10 gXl
100 g / l # 14.5 g / l
150 g / l, 18.5 g / l
Example 7
Re-extraction of the organic phase with oxalic acid
A volume of organic phase is brought into contact with a volume of aqueous phase with 5 z of oxalic acid at 400 C. After 1 h the stripping is 96 S. After 6 h the stripping is 99
Example 8
Selectivity with respect to platinum
One volume of the following aqueous solution was mixed
Pt "25 g / l
HCl: 3M
NaCl: 2.5 M with a volume of the following organic phase
compound of Example 1 to 150 g / l
thinner: "Solvesso 200" (R) + 5% TBP
The amount of platinum extracted is 0.5 g / l or 2%.

Under the same conditions (see Example 6) 99% gold is extracted, a separation factor equal to 5000.

Claims (13)

claims

 wherein: R 1 is a hydrocarbyl group having 2 to 10 carbon atoms, substituted by at least one ring

 1. New carbonate polyethers bearing cyclic carbonate groups of general formula R2 or R3, which may be identical or different, are linear or branched alkyl groups containing 2 to 20 carbon atoms or aromatic groups optionally substituted with one or more lower alkyl radicals, n and p are independently between 0 and 40 but not zero simultaneously. 2 - New carbonate-polyethers bearing cyclic carbonate groups according to claim 1, characterized in that they correspond to the general formula:

  wherein R2 and R3 have the same meaning and n and p are independently between 0 and 40 but not zero simultaneously. 3 - New carbonate-polyethers bearing cyclic carbonate groups according to claim 2 characterized in that R2 or R3 is an alkyl group having two to four carbon atoms or a phenyl group optionally substituted by a lower alkyl radical and n and p are independently between 0 and 20 but not zero simultaneously. 4 - New carbonate-polyethers bearing cyclic carbonate groups according to claim 3, characterized in that they correspond to the following general formula

 n and p having the same meaning as in claim 3. 5 - Process for synthesizing carbonates according to claim 1, characterized in that 2,3-carbonyldioxypropyl chloroformate is reacted with an alcohol alone or in a mixture of general formula

 or R1 and R2 and n have the meanings given in claim 1, OH groups replacing the groups

  optionally, at a temperature between -100 and + 200 C and in the presence of an acid acceptor. 6 - Composition, especially useful as extracting organic solution of metal values, characterized in that it comprises at least one aromatic solvent and at least one compound according to one of claims 1 to 4. 7 - Composition especially useful as extracting organic solution of metal values according to claim 4 characterized in that the compound is present at a concentration of between 10 and 180 g per liter of solvent. 8 - Composition especially useful as extracting organic solution of metal values according to one of claims 6 or 7 characterized in that it further comprises at least one trialkylphosphate. 9 - Composition especially useful as extracting organic solution of metal values according to claim 8 characterized in that the concentration of trialkylphosphate is less than 10% by weight relative to the solvent.  10 - Process for separating metal values from an aqueous solution containing them by liquid-liquid extraction characterized in that said aqueous solutions are brought into contact with an organic solution according to one of claims 6 to 9 in a manner 2 at least a part of the metal values are extracted by the organic solution and then separating the aqueous solution from the organic solution and in that the metal values contained in the organic solution are recovered by contacting the organic solution. the latter with an aqueous re-extraction medium. 11 - Process for separating metal values from an aqueous solution containing them according to claim 10 characterized in that the metal values are chosen from the group consisting of Zn (II), Cd (IL), Hg (II), Fe (III), Co (II), Cu (I! R Rh (III), Cu (II), Pd (II), Pt (II), Mo (V), V (IV), Pb (II), Ag (I), (III), Ga (III) and Na (I), K (I), Hg (I), U (IV), U (VI) and lanthanides with oxidation (II), (III) or (IV). 12 - Process for separating metal values from an aqueous solution containing them according to claim 11, characterized in that the recovery of the metallic value contained in the organic phase is ensured by an aqueous solution of an organic acid, preferably oxalic acid. 13 - Process for separating metal values from an aqueous solution containing them according to one of claims 10 to 12, characterized in that the organic solution is previously treated with an acidified aqueous solution.